This study investigates the development of the microstructure in the interconnection zone of an IN718/Al/IN718 couple obtained by the Transient Liquid Phase Bonding (TLPB) process at 1000 °C. The crystal structure, composition and orientation of the phases formed during joining were examined by SEM-EDS EBSD. The results showed that the interconnection zone is a multilayered region, constituted mainly by sigma (σ), Laves and α-Cr phases and the AlNi intermetallic. The evolution of the microstructure over time shows that the topologically close-packed (TCP) phases grow as columnar grains, while the AlNi phase forms exiaquied grains. The AlNi phase is split into two layers, Al-rich and Ni-rich, both having the same crystal structure but different chemical composition. EBSD mapping revealed that there is no grain boundary along the split line, suggesting that splitting results from a solid-state transformation requiring no nucleation. At longer bonding time, the AlNi phase is enriched in Ni and presents nanoprecipitates homogeneosly dispersed. These results provide experimental data that contribute to the understanding of TLPB of superalloys.

这项研究调查了通过瞬态液相键合（TLPB）工艺在1000°C下获得的IN718 / Al / IN718对的互连区中微结构的发展。通过SEM-EDS EBSD检查接合期间形成的相的晶体结构，组成和取向。结果表明，互连区是一个多层区域，主要由σ（σ），Laves和α组成。-Cr相和AlNi金属间化合物。随着时间的推移，微观结构的演变表明，拓扑紧密堆积的（TCP）相以柱状晶粒的形式生长，而AlNi相则形成了绝大部分的晶粒。AlNi相被分成两层，即富Al和富Ni，两者具有相同的晶体结构但化学组成不同。EBSD测绘表明，沿分裂线没有晶界，这表明分裂是由于不需要晶核的固态转变而产生的。在更长的键合时间下，AlNi相富含Ni，并且呈现出均匀分散的纳米沉淀。这些结果提供了有助于理解高温合金TLPB的实验数据。